myonecrosis

Myonecrosis is the death and tissue necrosis of skeletal muscle. It can arise from various insults, including ischemia from vascular injury or compartment syndrome, direct muscle trauma, and infection with toxin-producing bacteria. When infection is involved, it is often rapid and life-threatening, and may occur as clostridial myonecrosis (gas gangrene) or as part of broader necrotizing soft tissue infections.

Causes and pathophysiology include ischemic injury that leads to hypoxia and cell death, and bacterial infections that release potent exotoxins. Clostridium species, especially Clostridium perfringens, are classically associated with gas gangrene, producing enzymes and toxins such as alpha-toxin that destroy muscle and facilitate gas production in tissues. Nonclostridial pathogens can also cause myonecrosis in the context of necrotizing fasciitis or polymicrobial infections. Gas formation, tissue edema, and rapidly spreading necrosis are common in clostridial cases.

Clinical features typically begin with sudden severe pain in a affected limb, swelling, and systemic signs such as fever, tachycardia, and hypotension. Crepitus or palpable gas may be detected. Laboratory findings often show elevated white blood cell count, creatine kinase, and lactate. Diagnosis is clinical but supported by imaging (radiographs, CT, or MRI showing gas in soft tissues) and surgical exploration when indicated.

Management requires prompt surgical debridement or fasciotomy, broad-spectrum antibiotics covering anaerobes and gram-positive/negative organisms, and supportive care. Penicillin G plus clindamycin is a common starting regimen for suspected clostridial infection, with adjustments based on culture results. Hyperbaric oxygen therapy may be used in selected cases. Prognosis depends on the speed of intervention; delays increase mortality.